atan

Definition and usage

The atan() function returns the arctangent tangent of a numeric value, which is between -PI/2 and PI/2.

Example

This example calculates the arctangent of different values:

 <?php
echo ( atan ( 0.50 ) ) ;
echo ( atan ( - 0.50 ) ) ;
echo ( atan ( 5 ) ) ;
echo ( atan ( 10 ) ) ;
echo ( atan ( - 5 ) ) ;
echo ( atan ( - 10 ) )
?>

Try it yourself

grammar

 atan( x )

illustrate

atan() function returns the arctangent value of x , in radians. atan() is the inverse function of tan() , which means that every value in the atan() range is a==tan(atan(a)) .